This invention relates generally to a distributorless and contactless ignition system useable in an internal combustion engine and particularly to a magnetic sensor employing a Hall-effect device operatively connected to an engine crankshaft to enable sensing the rotative position thereof.
Ignition systems for modern internal combustion engines often employ a contactless distributor circuit which produces a predetermined series of output pulses suitable for firing the spark plugs of the engine in a predetermined firing order sequence. In such circuits passive sensors such as variable reluctance magnetic elements are positioned within the distributor to threshhold detect or zero crossing detect a waveform generated by a passing lobe, notch or tooth formed of appropriate material and which is connected to the rotatable distributor shaft. Distributorless ignition systems are also known in the prior art wherein a large plurality of magnetic responsive elements produce unidirectional pulses from magnetic fields. Typically, two or more magnetic sensor elements are utilized in applications wherein a first sensor provides a reference pulse and a second sensor generates a large plurality of other related timing pulses. Alternatively, each of two pickups or transmitters used in conjunction with a disc having a large plurality of teeth or gaps are applied, respectively, to differing encoding elements utilizing four stage binary counting to produce the requisite firing order signals. Such ignition systems, when utilizing the distributor concept, incur the inherent additional weight, radio frequency interference, mechanical complexities, and propensity for misadjustment and tampering involved with the incorporation of a distributor in the ignition system. In distributorless systems, in addition to the above reasons, the plural magnetic sensors increase system costs and complexity.